It is well known that reduction of tissue temperature can greatly retard or suspend tissue necrosis. Recently, considerable attention has been given to apparatus and methods of cooling body organs to protect them from the consequences of disease and accidental trauma, as well as during the trauma of emergency and elective surgery.
One approach to organ cooling is to lower the temperature of the entire body, and thus all of its organs with it. This approach requires a gradual, extended cooling period to be accomplished safely, and still produces undesirable side effects. Because the body naturally fights to preserve heat in the vial organs, it can take hours to cool the body's organs.
Somewhat more focused techniques and apparatus for organ cooling have been developed that provide for cooling the blood supply to the target organ by placing a cooling structure within a blood vessel that supplies the entire target organ or a substantial portion thereof. However, cooling an organ by cooling its blood supply requires considerable cooling power; high turbulence around the cooling transfer region to promote heat transfer across the cooling tip area, and it can still take a considerable amount of time to cool the target organ and the cooled blood can precipitate undesirable side effects, such as shivering and patient discomfort.
An alternative to indirectly cooling an organ by cooling the entire body or the blood that supplies an organ is to directly cool the target tissue within an organ. For example, myocardial tissue is routinely preserved in a healthy state in the absence of an oxygen rich blood supply during “open heart” procedures by interrupting blood flow to the heart and packing it with ice or placing it into an ice-filled basin. Although an ice bath plunge can provide immediate effective results for limiting tissue damage, it is clearly an “invasive” procedure, as are some other techniques that provide for surface application or envelopment of an organ with a cooling apparatus.
In view of the above limitations, it would be desirable to minimize tissue necrosis as quickly and completely as possible using a minimally invasive technique.